Audio operational amplifiers may be used for many applications, including phono preamplification, other forms of audio preamplification, balanced-to-single-ended conversion, adding audio signals, subtracting audio signals, high-pass filtering, low-pass filtering, graphic equalizing, and/or the like. Audio signals may be processed by circuitry for signal conditioning that includes audio operational amplifiers. The signal conditioning may include functions such as gain, mixing, filtering, driving an audio power amplifier, and/or the like.